Field of Invention
The present invention relates to a power converter, a secondary side controller and a short circuit determination method for a current sensing resistor of the power converter; particularly, it relates to such power converter, such secondary side controller and such short circuit determination method which are capable of checking whether an undesirable short circuit occurs in the current sensing resistor, so that the power converter can be well protected.
Description of Related Art
Typically, in a conventional isolated type AC-DC converter wherein a transformer is employed to isolate an input terminal from an output terminal, a primary side of such isolated type AC-DC converter has already been equipped with an input current monitoring mechanism. Nevertheless, because the requirement for the accuracy of the over current protection (OCP) or constant current (CC) operation for the output current of the power converter has become higher and higher, in certain applications, it is preferred to directly monitor the output current by a current sensing resistor connected to an output terminal of the power converter, for more accurate control of the output current.
However, there is a disadvantage associated with this method which monitors the output current only by a current sensing resistor connected to the output terminal of the power converter, that is: when a short circuit occurs in the current sensing resistor, the power converter cannot detect whether the output current is over-loading. Under such circumstance, the power converter cannot be properly protected due to lack of accurate information.
In view of the above, to overcome the drawback in the prior art, the present invention proposes a power converter, a secondary side controller and a short circuit determination method which are capable of checking whether an undesirable short circuit occurs in the current sensing resistor, so that the power converter can be well protected.